1. Field of the Invention
The present invention relates generally to the field of heating ovens. More particularly, the present invention relates to convective heating reflow soldering ovens for electronic parts.
2. Description of The Prior Art
Heating ovens have been widely used for various home use or industrial purpose. The following thirteen (13) patents were uncovered in the pertinent fields of the art.
1. U.S. Pat. No. 2,369,706 issued to Altamore on Feb. 20, 1945 for "Recirculating System for Gas Fired Ovens" (hereafter "Altamore Patent").
2. U.S. Pat. No. 2,731,732 issued to Harris, Jr. et al. on Jan. 24, 1956 for "Apparatus and Method for Setting and Drying Moisture Settable Ink" (hereafter "Harris Patent").
3. U.S. Pat. No. 2,795,054 issued to Bowen III on Jun. 11, 1957 for "Method and Apparatus for Heat Recovery from Drying Oven Effluents" (hereafter "Bowen Patent").
4. U.S. Pat. No. 2,981,528 issued to Culp on Apr.25, 1961 for "Drying System" (hereafter "Culp Patent").
5. U.S. Pat. No. 3,163,694 issued to Ipsen on Dec. 29, 1964 for "Recirculating Heat Treating Furnace" (hereafter "Ipsen Patent").
6. U.S. Pat. No. 3,548,514 issued to Smith et al. on Dec. 22, 1970 for "Heating Apparatus Employing Radiant and Convective Heat Means Usable as a Bake Oven" (hereafter "Smith Patent").
7. U.S. Pat. No. 3,564,648 issued to Snow on Feb. 23, 1971 for "Shucking Of Bivalves" (hereafter "Snow Patent").
8. U.S. Pat. No. 3,854,918 issued to McKinstry on Dec. 17, 1974 for "Method for Continuous Heat Treating of Glass Articles" (hereafter "McKinstry Patent").
9. U.S. Pat. No. 3,999,306 issued to Koch, II et al. on Dec. 28, 1976 for "Anti-pollution Drying Oven" (hereafter "Koch Patent").
10. U.S. Pat. No. 4,012,190 issued to Dicks et al. on Mar. 15, 1977 for "Annealing Lehr" (hereafter "Dicks Patent").
11. U.S. Pat. No. 4,448,578 issued to Brunet et al. on May. 15, 1984 for "Curing Oven for Enameled Wire and Control System Therefor" (hereafter "Brunet Patent").
12. U.S. Pat. No. 4,548,191 issued to Hwang on Oct. 22, 1985 for "Food Cooking Oven and Method" (hereafter "Hwang Patent").
13. U.S. Pat. No. 4,878,838 issued to Verheyden on Nov. 7, 1989 for "Process for the Thermal Treatment of More Particularly Substantially Flat Bodies of a Ceramic Material and Continuous Furnace for the Performance of the Process" (hereafter "Verheyden Patent").
The Altamore Patent disclosed an early gas fired oven. The oven has a recirculating system utilizing a blower device at one end of the conveyor. The blower device circulates the airflows longitudinally.
The Harris Patent discloses an apparatus and method for setting and drying moisture settable ink which utilizes a means for circulating and recirculating gas in the drying chamber comprised of an exhaust impeller to withdraw gas from a plenum. An impeller directs air way from a central region, circulating the air in two directions which is distributed by a plurality of spaced apart inverted troughs positioned over the conveying web. The circulated air is directed toward small inverted troughs with gaps at the sides and is specifically designed to distribute the air along a flat paper surface at the end of a conveyor system.
The Bowen Patent discloses a method and apparatus for heat recovery from drying oven effluents. In the oven the gases are continuously internally recirculated and a predetermined volume of effluents is continuously exhausted from the oven in order to maintain the concentration of solvent vapors at a safe level.
The Culp Patent discloses a drying system. The system comprises a plurality of open flame convection heaters focusing a stream of gaseous heating medium from above a conveyor into a chamber, in which the gaseous heating medium can circulate above and below the conveyor to establish accurate temperature distribution.
The Ipsen Patent discloses a recirculating heat treating furnace including a baffled impeller for moving air 360 degrees around the work object. The baffled impeller circulates air laterally toward a combustible gas which is also directed laterally toward the object.
The Smith Patent disclosed a heating apparatus employing radiant and convective heat means usable as a bake oven. Parallel heat radiating tubes supply heat to the chamber and in addition, the tubes have nozzle configurations which inject pressurized gas into the chamber thereby circulating gas in the chamber.
The Show Patent discloses an apparatus designed for shucking bivalves such as clams, oysters and scallops by means of enveloping said bivalves in a concentrated high-temperature medium. The heat source used in this apparatus is a flammable gas and an exhaust system is used un conjunction with the applied heat source which has an interference means presenting a negligible radiating surface which allow the flames to pass upwardly and around said interference means to form a uniform bed of flame.
The McKinstry Patent Discloses a method for continuous heat treating of glass articles. The method involves a process wherein burning gases are injected tangentially into the combustion zone and establish a swirling movement of the burning gas around the outside of the tunnel due to the cylindrical nature of the chamber, thereby allowing gases to freely swirl around the articles introduced into the chamber by conveyor.
The Koch Patent discloses an anti-pollution drying oven for drying applied coating material having volatile properties. It comprise a housing defined by a heating enclosure and an oven enclosure, using a flame heat source in conjunction with an air circulating means disposed in the heating enclosure. The air is directed toward an air inlet opening in which the conveying articles are disposed.
The Dicks Patent discloses an annealing lehr, used primarily for annealing glassware, in which the ware passes, by means of a conveyor, through a chamber where gases pass upward through a duct located at the central region of the chamber and are distributed by a circulating impeller outward and downwardly through configured ducts located at the sides of the chamber. The ducts at the sides of the chamber causes the gases to circulate to the ware from under the conveyor. One particular feature of the Dicks Patent relates to its method of circulating of the airflow. The airflow in the Dicks Patent process circulates around underneath the conveyor whereas in the present invention, the airstream interfaces with the circuit board surface from above.
The Brunet Patent discloses a curing oven for enameled wire. The curing oven utilizes a heat exchanger to preheat the circulated air.
The Hwang Patent discloses a food cooking oven. The oven has an impeller for directing a cooking medium toward a baffle which separates the cooking medium into two streams. One stream is caused to flow in the direction of the conveyor product, and the other stream is caused to flow in a direction opposite to the direction of product movement.
The Verheyden Patent discloses a thermal treatment of flat ceramic bodies using conveying rollers. The process comprises a heating zone, a firing zone and a cooling zone. A blower can be incorporated in the central region of the furnace where the gases in the heating zone are conducted in contraflow with the conveying direction of the bodies. The process also utilizes a bypass system for circulating gases around the heating zone and the heating zone itself is partitioned off. The parts then go to a firing zone where the bodies are very rapidly heated. The gasses before and after the central zone are flowing in the same direction from right to left.
There is a significant need for a solder reflow oven which comprises the many advantages discussed herein and which are not disclosed or made obvious by the prior art patent.